1. Field
The present application relates to gas turbines, and more particularly to an arrangement and method to minimize flow induced vibration in a gas turbine exhaust diffuser.
2. Description of the Related Art
The turbine exhaust cylinder and the turbine exhaust manifold are coaxial gas turbine casing components connected together establishing a fluid flow path for the gas turbine exhaust diffuser. The fluid flow path includes an inner flow path and an outer flow path defined by an inner diameter delimiting an outer conical surface of the inner flow path and an outer diameter delimiting an inner conical surface of the outer flow path, respectively. Tangential and/or radial struts, which include the corresponding strut shields that are the aerodynamic surfaces around the tangential and/or radial struts, are arranged within the fluid flow path and serve several purposes such as supporting the flow path and provide a pathway for lubrication piping. Turbine exhaust cylinder (TEC) and turbine exhaust manifold (TEM) struts are arranged in circumferential rows, for example, a circumferential row of TEC struts and a circumferential row of TEM struts in a flow direction, and extend between the outer conical surface and the inner conical surface. Every other TEC strut may be circumferentially aligned (same circumferential location) with a TEM strut.
At certain conditions, the exhaust flow around the struts can cause vibrations of the inner and outer diameter of the TEC and the TEM due to strut flow unsteadiness. The strut flow unsteadiness may cause large oscillations in flowpath pressures that force the flowpath structure to vibrate or even resonate strongly. These vibrations are a potential contributor to damage occurring on the flow path of the TEM and the TEC. This damage to the diffuser flow path may require replacement or repair.